python - Django simple_tag 和设置上下文变量

Question

我正在尝试使用 simple_tag 并设置上下文变量。我使用的是 django 的 trunk 版本:

from django import template

@register.simple_tag(takes_context=True)
def somefunction(context, obj):   
    return set_context_vars(obj)

class set_context_vars(template.Node):
    def __init__(self, obj):
        self.object = obj
    
    def render(self, context):
        context['var'] = 'somevar'
        return ''

这不会设置变量，但如果我对 @register.tag 执行非常类似的操作，它会起作用，但对象参数不会传递...

谢谢!

Answer 1

您在这里混合了两种方法。 simple_tag 只是一个辅助函数，它减少了一些样板代码，并且应该返回一个字符串。要设置上下文变量，您需要(至少对于普通的 django)write your own tag使用渲染方法。

from django import template

register = template.Library()


class FooNode(template.Node):

    def __init__(self, obj):
        # saves the passed obj parameter for later use
        # this is a template.Variable, because that way it can be resolved
        # against the current context in the render method
        self.object = template.Variable(obj)

    def render(self, context):
        # resolve allows the obj to be a variable name, otherwise everything
        # is a string
        obj = self.object.resolve(context)
        # obj now is the object you passed the tag

        context['var'] = 'somevar'
        return ''


@register.tag
def do_foo(parser, token):
    # token is the string extracted from the template, e.g. "do_foo my_object"
    # it will be splitted, and the second argument will be passed to a new
    # constructed FooNode
    try:
        tag_name, obj = token.split_contents()
    except ValueError:
        raise template.TemplateSyntaxError, "%r tag requires exactly one argument" % token.contents.split()[0]
    return FooNode(obj)

这可以这样称呼:

{% do_foo my_object %}
{% do_foo 25 %}